This invention relates to an automatic hand weapon which has a gas tap formed by a radial bore in the barrel and a cylinder which has an inlet channel constituting a continuation of the radial bore and further, a gas piston displaceably received in the cylinder and provided with a return spring for actuating elements of the breechblock.
In automatic hand weapons it is conventional to utilize the pressure of the projectile-propelling gases for actuating the breechblock or components thereof. For tapping such a control pressure which may be as high as 2000 bar, in the front sight support there is provided a nozzle arrangement which communicates with a gas tapping bore in the barrel. A nozzle part which has differently formed grooves and which forms part of the nozzle arrangement is adjustable in such a manner that the gas quantity escaping from the barrel is admitted into one of two passages of different cross sections and affects a piston and a piston rod for actuating the breechblock.
Because of propellant residues which pass with the gas through the nozzle arrangement, even after a few shots substantial soiling of the weapon components may take place. Further, the automatic actuation of the breechblock parts as outlined above is effected non-uniformly: such an actuation depends upon the ammunition fired. Particularly in case of firing rifle grenades with normal ammunition or propellant charges the pressure may increase substantially or may last longer.
After firing, the gas is released to the atmosphere from the nozzle arrangement by means of the closing spring surrounding the piston rod, along the same path back into the barrel and into the atmosphere. A self-cleaning of the various ports and channels which in part are arranged at an angle, cannot be achieved with such a process.